Connection control method for mobile communication, mobile communication management apparatus and mobile station apparatus

The present invention generally relates to the field of mobile communication and more particularly relates to an efficient mobile station connection control method in a mobile communication network including a small and low-cost private base station (Home e-NodeB) dedicated for certain users as well as a mobile communication management apparatus and a mobile station for implementing that method.

Presently, it is being discussed and proposed to introduce a very small base station targeted for certain users for implementing FMC (Fixed and Mobile Convergence) services (see “Requirements for LTE Home eNodeBs”, RP-070209, 3GPP TSG RAN #35, Lemesos, Cyprus, 6-9 Mar. 2007). In LTE (Long Term Evolution), whose specification development is being currently ongoing, as a successor to the third generation radio access scheme, such very small base stations targeted for certain or specified users are collectively referred to as Home eNBs (or Home e-NodeBs). The Home eNB is a so-called plug-and-play type of apparatus that a user can buy and install at a desired location without the necessity of operator's manual installation, maintenance and management.

The Home eNB may have overlapped geographical areas with public targeted base stations (which are conveniently referred to as “macro eNBs”) that are constituents of an existing public communication network. Also, its serving frequency is enabled in combination with frequencies served by adjacent macro eNBs. As a result, when a mobile station migrates from an area covered by an adjacent macro eNB (referred to as a “macro cell”) into a serving area of the Home eNB, efficient cell search and/or handover may be required.

In a conventional mobile communication network, abase station uses common control channels such as BCHs to broadcast center frequencies used by adjacent base stations for fast inter-frequency cell search and fast inter-frequency handover at a mobile station. Before placing a new base station into service, an operator investigates the center frequencies used by adjacent base stations serving other coverage areas bordering a coverage area served by that new base station and then generates an adjacent cell list, which is installed in the new base station. A mobile station could receive a common channel such as a BCH broadcast from a base station providing a resident cell and determine the center frequencies used in other cells adjacent to that cell. Among many possible center frequencies, the mobile station could identify the center frequencies presently used in the adjacent cells, which results in faster cell search and handover at cell transition. As a result, the mobile station can select optimal cells while maintaining communication quality of dedicated links.

Problem to be Solved by the Invention

However, conventional mobile communication control methods cannot be directly applied to a system to which a certain user targeted base station for certain or specified users such as a Home eNB is introduced. For example, when a user leaves home, the user may power off a radio unit of the Home eNB. Then, when the user comes home, the user may power on the radio unit again. Thus, the Home eNB may be suspended and restarted iteratively depending on a user's behavior, and thus there is a likelihood that whenever the Home eNB is restarted, different center frequencies may be used. Assuming that the Home eNB is listed in the adjacent cell lists for adjacent public communication eNBs (macro eNBs), whenever the Home eNB is restarted, some operations and signaling for updating the center frequency for the Home eNB in the adjacent cell lists may have to be performed. It is predicted that a large number of Home eNBs may be installed, and thus the above-mentioned adverse effect could not be ignored for the whole network.

On the other hand, the center frequency used by the certain user targeted Home eNB has to be known to only mobile stations permitted to access the Home eNB. Even if it is broadcast from a macro eNB to many unspecified mobile stations, unnecessary measurement and signaling may be increased in mobile stations that are not permitted to access the Home eNB. As a result, interference to other cells or battery energy consumption in the mobile stations may be unnecessarily increased.

For the above-mentioned reasons, it would not be practical to list information regarding the Home eNB in the adjacent cell list for the macro eNB and update it constantly.

One object of the present invention is to provide a connection control method that enables efficient cell search and fast handover in a mobile communication system including a Home eNB while preventing increase in power consumption in a mobile station.

Another object of the present invention is to provide a mobile communication management apparatus for implementing the above connection control method and a mobile station apparatus for use in the system.

Means for Solving the Problem

In order to achieve the above objects, when a mobile station belonging to a mobile station group having a certain attribute, such as a mobile station permitted to access abase station for certain users (Home eNB), enters or now exists within a location registration area (tracking area) associated with that Home eNB, for example, a network side management apparatus detects the mobile station and transmits a center frequency and/or other connection parameters (including scrambling code, a cell ID and/or others) used by the Home eNB to the mobile station in a dedicated manner. The transmitted connection parameters are stored in the mobile station until a message for discarding the connection parameters is received from a network.

Specifically, according to a first aspect of the present invention, a connection control method is provided. In this method, connection information with a certain user targeted base station is transmitted to a mobile station belonging to a mobile station group associated with the certain user targeted base station in a dedicated channel corresponding to the mobile station or a multicast channel corresponding to the mobile station group via a public targeted base station where the mobile station resides.

According to a second aspect of the present invention, a connection control method includes detecting that a mobile station permitted to access a certain user targeted base station has entered or occurred within a location registration area associated with the certain user targeted base station; transmitting connection information including at least frequency information presently used by the certain user targeted base station and ID information for the certain user targeted base station to the mobile station in a dedicated manner; and performing cell search at the mobile station based on the connection information.

According to a third aspect of the present invention, a mobile station for use in a mobile communication system including a certain user targeted base station is provided. The mobile station includes a dedicated information acquisition unit configured to, if the mobile station belongs to a mobile station group associated with the certain user targeted base station, acquire connection information for the certain user targeted base station in a dedicated manner; a broadcast information acquisition unit configured to acquire broadcast adjacent cell information on an adjacent cell in a public targeted base station where the mobile station resides; and a cell search determination unit configured to perform cell search based on the acquired connection information for the certain user targeted base station and the broadcast adjacent cell information.

According to a fourth embodiment of the present invention, a mobile communication management apparatus for use in a mobile communication system including a certain user targeted base station is provided. The mobile communication management apparatus includes a memory unit configured to store identification information for the certain user targeted base station in association with mobile station information for a mobile station having a predefined attribute associated with the certain user targeted base station and frequency information presently used by the certain user targeted base station; a location monitoring unit configured to monitor location of the mobile station; an indication information generation unit configured to, when the location monitoring unit detects that a mobile station having the predefined attribute has entered or occurred within a location registration area associated with the certain user targeted base station, generate connection information with reference to the memory unit, the connection information including at least the identification information and the frequency information for the certain user targeted base station; and a transmitting unit configured to transmit the connection information to the mobile station.

According to the aspects of the present invention, efficient cell search and fast handover are achieved in a mobile communication system including a Home eNB while preventing increase in power consumption in a mobile station.

FIG. 1 schematically illustrates an exemplary mobile communication system to which the present invention is applied;

FIG. 2 is a sequence diagram illustrating exemplary connection control in the mobile communication system in FIG. 1 ;

FIG. 3 is a block diagram illustrating an exemplary arrangement of a mobile station for use in the mobile communication system in FIG. 1 ;

FIG. 4 illustrates an exemplary connection parameter table stored in a memory unit in the mobile station in FIG. 3 ; and

FIG. 5 is a block diagram illustrating an exemplary arrangement of a mobile communication management apparatus or MME for use in the mobile communication system in FIG. 1 .

10 : mobile station

11 T: transmit antenna

11 R: receive antenna

12 : base station targeted transmitting unit

13 : base station targeted receiving unit

14 : user interface unit

15 : common control channel information acquisition unit (common information acquisition unit)

16 : dedicated control channel information acquisition unit (dedicated information acquisition unit)

17 : memory unit

17 t : connection parameter table

18 : cell search determination unit

20 : Home eNB (certain user targeted base station)

21 : home cell

30 : macro eNB (public targeted base station)

31 : macro cell

35 : tracking area (location registration area)

40 : upper node

40 A: MME (mobile communication management apparatus)

41 : network interface

42 : base station targeted receiving unit

43 : mobile station location monitoring unit

44 : indication information generation unit

45 : Home eNB-UE association database

46 : Home eNB frequency database

47 : base station targeted transmitting unit

Preferred embodiments of the present invention are described below with reference to the accompanying drawings. FIG. 1 schematically illustrates an exemplary arrangement and fundamental operations of a mobile communication system according to embodiments of the present invention. In the mobile communication system illustrated in FIG. 1 , multiple radio base stations 30 A, 30 B, 30 C, . . . constituting a public communication network form macro cells 31 A, 31 B, 31 C, . . . , respectively, in such a manner that the macro cells 31 A, 31 B, 31 C, . . . have overlapped boundaries. The radio base stations 30 forming the macro cells 31 are referred to as macro eNBs. In the macro eNB 30 A, a carrier wave having a center frequency f 1 (simply referred to as “frequency f 1 ” hereinafter) is used. In the macro eNB 30 B, frequencies f 1 and f 2 are used, and in the macro eNB 30 C, the frequency f 2 is used.

The macro eNBs 30 A through 30 C are logically connected with an upper management node 40 over a logical interface S 1 . For example, the upper management node 40 may include a MME (Mobile Management Entity) 40 A and a UPE (User Plane Entity) 40 B. The UPE 40 B may be also referred to as a S-GW (Serving Gateway).

A Home eNB 20 working as a base station serving for certain users is provided within the macro cell 31 A and presently uses a frequency f 3 . The Home eNB 20 is also logically connected with the upper management node (MME/UPE) 40 over the logical interface S 1 .

A mobile station 10 presently having a predetermined attribute associated with the Home eNB 20 , such as a mobile station 10 permitted to access the Home eNB 20 , is traveling from the macro cell 31 C toward a home cell formed by the Home eNB 20 . The macro eNB 30 C for the macro cell 31 C broadcasts frequency information (f 1 , f 2 ) presently used in the adjacent macro eNB 30 B in a BCH. As a result, the mobile station 10 can search for the f 1 and f 2 being used as the frequencies for the destination cell 31 B.

The mobile station 10 enters not only the macro cell 30 B but also a tracking area (TA) 35 A that is a location registration area associated with the Home eNB 20 . Upon detecting that the mobile station 10 has entered the tracking area 35 A or has been found within the tracking area 35 A based on location information for the mobile station 10 (for example, the mobile station 10 has been powered on within the tracking area), the MME 40 A in the upper management apparatus 40 informs the mobile station 10 of the frequency f 3 being used by the Home eNB 20 as well as other connection parameters (such as a scrambling code, a cell ID, a tracking area ID or a frequency bandwidth) in a dedicated manner. In the illustration in FIG. 1 , the connection parameters (including the frequency f 3 ) for the Home eNB 20 are transmitted from the MME 40 A to the mobile station 10 via a DCCH (Dedicated Control Channel) and a SCH (Shared Channel) that is a physical dedicated control channel. These connection parameters are used for cell search and thus may be referred to as “cell search parameters” for convenience. In the illustration, the connection parameters are transmitted from the macro eNB 30 B to the mobile station 10 via the physical dedicated control channel SCH but may be transmitted via a SCH ongoing from the Home eNB 20 . Alternatively, a user may transmit a request for the connection parameters to the MME 40 A through the user's manual operation of the mobile station 10 , and upon reception of this request, the MME 40 A may transmit the connection parameters to the mobile station 10 in a dedicated manner.

On the other hand, the macro eNB 30 B broadcasts frequency information (f 1 , f 2 ) regarding adjacent cells over BCHs, and thereby the mobile station 10 can search for the frequencies f 1 , f 2 and f 3 . When the mobile station 10 actually approaches the home cell, the mobile station 10 can select any of the frequencies f 1 , f 2 and f 3 . For example, the mobile station 10 may select the frequency f 3 if the mobile station 10 is enabled to access the Home eNB 20 within the home cell 21 with fixed charge.

The mobile station 10 may have authority to access not only the illustrated Home eNB 20 but also another Home eNB. In this case, the mobile station 10 may be enabled to keep the connection parameters (cell search parameters) for both the Home eNBs. Alternatively, when the mobile station 10 exits from the tracking area 35 A, the mobile station 10 may be instructed by the MME 40 A via a dedicated channel to delete the connection parameters for the Home eNB 20 .

In this manner, according to this embodiment, the connection parameters are transmitted via the dedicated channel to only the mobile station 10 permitted to access the Home eNB 20 , which can prevent unnecessary signaling and interference with other cells. Also, the mobile station 10 does not receive cell parameter information for other Home eNBs that the mobile station 10 is not permitted to access. Thus, the mobile station 10 does not have to perform unnecessary cell search and can reduce power consumption.

FIG. 2 is a sequence diagram illustrating an exemplary connection control method in the mobile communication system in FIG. 1 . At step S 100 A, a center frequency presently assigned to the Home eNB 20 , a cell ID (and/or a scrambling code ID), ID information of the tracking area associated with that Home eNB and/or others are registered with MME 40 A and the Home eNB 20 for advance preparation to transmit the connection parameters (cell search parameters) to the mobile station 10 entering or existing within the tracking area associated with the Home eNB 20 . Since there is a higher likelihood that a different frequency from the previous frequency may be assigned as the center frequency after restart of the Home eNB 20 , for example, at step S 100 B, the center frequency may be accordingly updated in the MME 40 A in association with the cell ID. In addition, one or more mobile stations (UEs) permitted to access the Home eNB 20 are registered with the MME 40 A in advance.

At step S 101 , the mobile station 10 migrates into an area for an adjacent macro eNB 30 B deployed within the tracking area 35 A associated with the access permitted Home eNB 20 . At step S 201 , the macro eNB 30 B broadcasts presently used frequency information and/or ID information for the tracking area over a common control channel such as a BCH. At step S 102 , the mobile station 10 receives the BCH from the macro eNB 30 B, recognizes that the mobile station 10 itself has moved to a different tracking area 35 A based on a comparison between the previous tracking ID information and the received ID information, and transmits a TA Update signal to the macro eNB 30 B. At step S 202 , the macro eNB 30 B forwards the TA Update signal to the upper apparatus MME 40 A.

At step S 301 , the MME 40 A monitors the location of the mobile station (UE) 10 at the level of the tracking areas. Upon reception of the TA Update signal, at step S 302 , the MME 40 A detects that the mobile station 10 has entered or now exists in a new tracking area 35 A, for example, that the mobile station 10 has been powered on within the tracking area 35 A. At step S 303 , the MME 40 A searches for the center frequency of a Home eNB 20 associated with this tracking area 35 A. For the mobile station 10 , only one Home eNB 20 may not be associated with the tracking area 35 A. In other words, the mobile station 10 may be permitted to access two or more Home eNBs within the same tracking area 35 A. Also in this case, necessary information is automatically transmitted from each Home eNB to the MME 40 A at the advance preparation steps S 100 A and S 100 B, and thus the MME 40 A can store the information.

At step S 304 , as a result of the search, the MME 40 A transmits the cell ID of the Home eNB and the center frequency f 3 presently used by the Home eNB over a dedicated channel to the macro eNB 30 B where the mobile station (UE) 10 currently resides. At step S 203 , the macro eNB 30 B establishes a connection with the mobile station 10 and then transmits the connection parameters including the cell ID and the center frequency in a dedicated control channel.

At step S 103 , the mobile station 10 adds and stores the transmitted cell parameters such as the center frequency and the cell ID as targets for the current cell search in a memory. Meanwhile, at step S 104 , the Home eNB 20 periodically transmits common control channels such as BCHs within the home cell 21 . At step S 105 , the mobile station 10 detects the Home eNB 20 during the cell search and establishes communications with the Home eNB 20 at the frequency f 3 .

The above-mentioned steps correspond to cell parameter (Home eNB information) transmitting sequence A.

Upon exiting from the tracking area 35 A associated with the Home eNB 20 at step S 106 , the mobile station 10 receives a common control channel from another macro eNB provided in a new tracking area where the mobile station migrates and detects that the mobile station 10 has moved to the different tracking area. At step S 107 , the mobile station 10 transmits a TA Update signal to a macro eNB for that tracking area. At step S 204 , the new macro eNB forwards the received TA Update signal to the MME 40 A. Since the MME 40 A monitors the location of the mobile station 10 at level of the tracking areas at step S 305 , the MME 40 A can confirm that the mobile station 10 has exited from the previous tracking area 35 A associated with the Home eNB 20 at step S 306 . At step S 307 , the MME 40 A instructs the new macro eNB to transmit a deletion instruction of information on the Home eNB 20 received at the mobile station 10 . At step S 205 , the new macro eNB establishes a connection with the mobile station 10 and then transmits the deletion instruction to delete the Home eNB 20 in a dedicated control channel. Upon reception of the dedicated control channel, the mobile station 10 deletes and discards the connection parameters such as the center frequency and the cell ID regarding the Home eNB 20 . The above-mentioned steps correspond to a Home eNB information deletion sequence.

The mobile station 10 can add and store the connection parameters (cell search parameters) for several Home eNBs in the sequence A. However, when the mobile station 10 leaves a certain Home eNB and is away a predetermined distance, it may be less necessary to keep the connection parameters for that Home eNB or it may be likely to receive the connection parameters for another new Home eNB from the upper node 40 through a macro eNB. Thus, it is desirable to apply the deletion sequence B together with the sequence A.

Note that the deletion sequence B can be applied to not only the case where the mobile station 10 has exited from the tracking area 35 A for the Home eNB 20 of interest but also the case where the mobile station 10 has disappeared, for example, the case where the mobile station 10 has been powered off in the tracking area 35 A. In this case, when the MME 40 A detects and confirms that the mobile station 10 has disappeared from the tracking area 35 A (S 305 , S 306 ) and then detects that the mobile station 10 appears in a tracking area not associated with the Home eNB 20 (S 301 , S 302 ), the MME 40 A informs the mobile station 10 via a new resident macro eNB 30 that the mobile station 10 should delete the connection parameters currently stored for the Home eNB (S 307 , S 205 ).

FIG. 3 schematically illustrates an exemplary arrangement of the mobile station 10 for use in the mobile communication system in FIG. 1 . The mobile station 10 includes a transmit antenna 11 T, a receive antenna 11 R, a base station targeted transmitting unit 12 , a base station targeted receiving unit 13 and a user interface unit 14 . The user interface unit 14 includes a microphone, a display, a numeric keypad and/or others. A signal processing unit including modulation and demodulation, encoding and decoding, frequency conversion and/or others is not directly relevant to the present embodiment and thus is not illustrated.

The mobile station 10 further includes a common control channel information acquisition unit 15 , a dedicated control channel information acquisition unit 16 , a memory unit 17 and a cell search determination unit 18 . The common control channel information acquisition unit 15 is connected with the base station targeted receiving unit 13 and acquires common control channel information broadcast in common control channels from a macro eNB or a Home eNB where the mobile station 10 resides. Note that the acquired information includes center frequency information used by adjacent base stations (macro eNBs) listed in an adjacent cell list configured to the currently resident macro eNB of the mobile station 10 . Of course, the acquired information may include a cell ID, a tracking area ID and/or others in addition to the center frequency information in the adjacent cell list. The common control channel information is supplied to the cell search determination unit 18 to use cell search.

The dedicated control channel information acquisition unit 16 is connected with the base station targeted receive unit 13 and acquires information transmitted from the MME 40 A in dedicated control channels via the currently resident macro eNB. For example, the acquired information may be connection parameters (cell search parameters) for an access authorized Home eNB associated with a tracking area where the mobile station 10 has newly entered or exists now. The connection parameters are required for the mobile station 10 to perform handover to the access authorized Home eNB and thus are stored in the memory unit 17 .

For the connection parameters for the access authorized Home eNB transmitted from the network side in dedicated control channels, for example, the memory unit 17 may store the presently used center frequency in association with the cell ID and keep them until a deletion instruction is transmitted in the same dedicated control channel. As mentioned above, there may be several Home eNBs that the mobile station 10 is permitted to access, and the memory unit 17 can store several pairs of the cell IDs and the center frequencies. Also, if a deletion instruction for certain connection parameters is received from the dedicated control channel information acquisition unit 16 , the memory unit 17 deletes that connection parameters (a pair of center frequency and cell ID).

The cell search determination unit 18 performs cell search on only the center frequencies used by adjacent eNBs listed in the adjacent cell list broadcast from the macro eNB in common control channels such as BCHs and the center frequency (connection parameter) for the Home eNB stored in the memory unit 17 . The mobile station 10 does not receive the connection parameters from the upper node for the Home eNBs that the mobile station 10 is not permitted to access, and thus even if the transmitted center frequencies for the Home eNBs are detected but are associated with cell IDs for Home eNBs unrelated to the transmitted cell IDs, the mobile station 10 does not attempt to connect to the Home eNBs.

If a pair of a center frequency and a cell ID for a certain Home eNB is deleted from the memory unit 17 , the cell search determination unit 18 does not perform the cell search for that Home eNB. Also, if there is no Home eNB whose pair includes a certain center frequency, the cell search determination unit 18 stops the cell search for that center frequency.

FIG. 4 illustrates an exemplary connection parameter table 17 t stored in the memory unit 17 of the mobile station 10 . In the connection parameter table 17 t , cell IDs for Home eNBs presently using certain center frequencies are listed in association with these center frequencies. In FIG. 4( a ), the center frequency #a is associated with Home eNBs for cell IDs # 1 and # 2 . Also, the center frequency #b is associated with a Home eNB for cell ID # 3 .

In this situation, when the connection parameters including the center frequency #c and the cell ID # 4 are transmitted from the network side in a dedicated control channel, as illustrated in FIG. 4( b ), the connection parameters are supplied from the dedicated control channel information acquisition unit 16 to the memory unit 17 and added to the connection parameter table 17 t . This means that the mobile station 10 has entered a tracking area associated with a Home eNB for cell ID # 4 or has been powered on within the tracking area. The mobile station 10 performs cell search based on center frequencies #a, #b and #c listed in the connection parameter table 17 t and the center frequencies related to an adjacent cell list broadcast from a macro eNB where the mobile station 10 presently resides.

In addition, upon reception of an instruction to discard a Home eNB for cell ID # 2 using center frequency #a and a Home eNB for cell ID # 3 using center frequency #b from the network side, as illustrated in FIG. 4( c ), the mobile station 10 deletes pairs corresponding to them from the connection parameter table 17 t . As a result, the mobile station 10 performs cell search based on center frequencies #a and #c remaining in the connection parameter table 17 t and center frequencies for adjacent eNBs broadcast from the resident macro eNB. If all cell IDs for a certain center frequency are deleted from the connection parameter table 17 t , the cell search is stopped for that frequency. On the other hand, if a cell ID associated with the center frequency remains in the connection parameter table 17 t , the cell search is performed for that frequency.

FIG. 5 illustrates an exemplary arrangement of an upper mobile communication management apparatus for use in the mobile communication system in FIG. 1 . In this illustration, the mobile communication management apparatus is the MME 40 A. The MME 40 A includes a network interface 41 , a base station targeted receiving unit 42 , a mobile station location monitoring unit 43 , an indication information generation unit 44 , a Home eNB-UE association database 45 , a Home eNB frequency database 46 and a base station targeted transmitting unit 47 .

For each Home eNB, the Home eNB-UE association database 45 stores the corresponding tracking area and mobile stations permitted to access the Home eNB in an associated manner. For each Home eNB, the Home eNB frequency database 46 stores a center frequency presently assigned to the Home eNB in an associated manner.

For each Home eNB, the mobile station location monitoring unit 43 monitors the locations of all mobile stations (UEs) permitted to access (connect with) the Home eNB at the level of tracking areas.

The indication information generation unit 44 generates connection indication information to be transmitted to the mobile station 10 that has entered a tracking area associated with a certain Home eNB or is now within the tracking area. This connection indication information is connection parameter information including a center frequency presently used by the Home eNB and a cell ID for the Home eNB. In addition, the indication information generation unit 44 generates deletion information to be transmitted to the mobile station 10 that has exited a tracking area associated with a certain Home eNB or has disappeared from the tracking area. The deletion information includes a pair of a center frequency and a cell ID for a Home eNB to be deleted from the connection parameter table 17 t in the mobile station 10 . The connection indication information and the deletion information are transmitted to the mobile station 10 in a dedicated control channel via a macro eNB in whose cell the mobile station 10 resides.

As mentioned above, according to the above embodiments of the present invention, for each mobile station permitted to access a certain Home eNB in a mobile communication network configured by introducing a large number of Home eNBs in an existing public communication network, when it is detected that the mobile station has entered a tracking area associated with the Home eNB or now exists within the tracking area, the connection parameters for that Home eNB are transmitted to the mobile station in a dedicated manner. Thus, systems can reduce unnecessary signaling and/or interference with other cells while mobile stations can reduce power consumption due to unnecessary measurement for access unauthorized Home eNBs or transmission of location update messages.

In the above-mentioned embodiments, authority to access the Home eNB 20 has been described as a predefined attribute associated with the Home eNB 20 , but the present invention is not limited to it. For example, existence within the tracking area 35 may be used as the attribute. Also in this case, the connection parameters are transmitted from the MME 40 A in a dedicated manner as trigger of membership of the mobile station 10 in a mobile station group having such an attribute.

In the above-mentioned embodiments, center frequencies and cell IDs operated by Home eNBs are transmitted and stored in mobile stations in an associated manner. Instead of or in addition to the cell IDs, scrambling code IDs may be used. Any other ID information for identifying the Home eNBs may be used. Instead of or in addition to the center frequencies, bandwidths or resource numbers as frequency information may be transmitted to mobile stations.

Dedicated control channels for transmitting the connection parameters including the center frequency and the cell ID for a Home eNB are not limited to a SCH, and any other channels for transmitting control information to individual users in a dedicated manner may be used.

Also, a deletion message for deleting the connection parameters may be transmitted to a mobile station a predefined time period after it is detected that the mobile station has exited from a tracking area. In the case where the mobile station migrates along the boundary of the tracking area, the mobile station may repeatedly enter and exit from the tracking area. Thus, it is desirable to delete the connection parameters after the location information on the mobile station is stabilized so that unnecessary addition and deletion of the connection parameters in the mobile station cannot be repeated.

This international patent application is based on Japanese Priority Application No. 2007-120260 filed on Apr. 27, 2007, the entire contents of which are hereby incorporated by reference.